Torque sensor, power assist device, power assist bicycle, and torque detection method

Abstract

The present invention is applicable to the field of bicycles and provides a torque sensor, a power-assisting device, a power-assisting bicycle, and a torque detection method. The torque sensor includes a central shaft; a first transmission member and a fourth transmission member, wherein the first transmission member is fixed to the central shaft, and the fourth transmission member is rotatably mounted on the central shaft, and the first transmission member and the fourth transmission member are arranged at intervals along the axial direction of the central shaft; a supporting cantilever, one end of which is fixed to the vehicle body, and the other end of which is rotatably provided with a second transmission member and a fifth transmission member, the second transmission member and the fifth transmission member are arranged coaxially, the second transmission member is engaged with the first transmission member, and the fifth transmission member is engaged with the fourth transmission member; a strain gauge is provided on the supporting cantilever. Through the design of the transmission structure of the bending moment, the dynamic torque on the central shaft 1 in the existing structure is converted into a stable bending moment for measurement. Compared with the existing technology, there is no need to use wireless transmission of torque, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

Description

Technical Field

[0001] The present invention belongs to the field of bicycles, and in particular relates to a torque sensor, a power-assisting device, a power-assisted bicycle and a torque detection method. Background Art

[0002] A power-assisted bicycle is a new type of two-wheeled vehicle, a type of bicycle. It uses batteries as an auxiliary power source, is equipped with an electric motor, and has a power-assist system. It is a new type of transportation tool that can realize the integration of human riding and motor assistance. In the field of power-assisted bicycles, there are two main types of motor installation positions. One is the mid-mounted motor, which is installed in the middle position of the vehicle body, that is, the motor at the five-way position. This is called a mid-mounted motor. The mid-mounted motor is connected to the frame and is connected to the rear wheel through a chain to transmit power. At the same time, pedals are installed on both sides of the motor. When the motor has no power supply, the rider can achieve human riding by pedaling, and the resistance is no different from that of a normal bicycle. The other type is installed in the hub of the bicycle, which is called a hub motor.

[0003] The torque sensor of a mid-mounted power-assisted bicycle is the core technology of the bicycle. It is the detection end that collects the riding torque during riding. The current mid-mounted power-assisted bicycle detects riding torque. The general method is to collect bending moment strain (the change in strain gauge resistance caused by bending moment strain) by attaching strain gauges on the rotating deformation shaft (rotating central shaft / deformed body on the central shaft). The voltage signal of the strain gauge after deformation is collected through a half-bridge / full-bridge. After amplification and A / D processing, the signal is transmitted to a stationary signal receiving end via wireless communication to collect dynamic bending moment. At the same time, the power supply of the strain gauge on the rotating shaft is powered by electromagnetic induction (in the form of a primary and secondary coil transformer). This method needs to deal with wireless power supply and wireless communication issues, which makes signal processing complicated and there is a risk of external electromagnetic signal interference, which requires electromagnetic shielding. Summary of the Invention

[0004] The torque sensor provided in the embodiment of the present invention is intended to solve the problem in the prior art that wireless power supply and wireless communication need to be processed, which leads to complicated signal processing, the risk of external electromagnetic signal interference, and the need for electromagnetic shielding.

[0005] The embodiment of the present invention is implemented as follows: a torque sensor for a mid-mounted motor of a power-assisted bicycle, comprising:

[0006] The middle bracket is used to connect the pedals;

[0007] a first transmission member and a fourth transmission member, wherein the first transmission member is fixed to the central shaft, the fourth transmission member is rotatably sleeved on the central shaft, and the first transmission member and the fourth transmission member are arranged in an axial direction of the central shaft at intervals;

[0008] A support cantilever, one end of which is fixed to the vehicle body, and the other end of which is rotatably provided with a second transmission member and a fifth transmission member, the second transmission member and the fifth transmission member being coaxial and integrally arranged, the second transmission member being engaged with the first transmission member, and the fifth transmission member being engaged with the fourth transmission member;

[0009] The strain gauge is provided on the supporting cantilever and is used to obtain a voltage change value generated by the strain gauge when the supporting cantilever is transmitted between the first transmission member and the second transmission member.

[0010] Furthermore, the supporting cantilever includes a first fixing plate and a second fixing plate that are spaced apart, and a connecting shaft connecting the first fixing plate and the second fixing plate, and the second transmission member and the fifth transmission member are rotatably fixed on the connecting shaft.

[0011] Furthermore, the supporting cantilever further includes a fixing member, which connects the first fixing plate and the second fixing plate and is used to be fixed to the vehicle body.

[0012] Furthermore, the strain gauges are provided on opposite sides of the first fixing plate and / or the second fixing plate that are perpendicular to the axial direction of the connecting shaft.

[0013] The present invention also provides a power assist device, including a third transmission member and the aforementioned power assist sensor. The third transmission member can be rotatably arranged on the central axis relative to the central axis and is located on the side of the fourth transmission member away from the first transmission member. The fourth transmission member can drive the third transmission member to rotate in one direction, and the third transmission member is used to connect the load.

[0014] Furthermore, the third transmission member is provided with a connecting portion, the connecting portion is provided with a first one-way linkage member, the fourth transmission member is fixed to the first one-way linkage member, and the fourth transmission member can drive the third transmission member to link with the first one-way linkage member.

[0015] The present invention also provides a power-assisted bicycle, comprising:

[0016] body;

[0017] a central motor, disposed on the vehicle body, wherein an output end of the central motor is provided with a sixth transmission member; and

[0018] In the aforementioned power-assisting device, the third transmission member is engaged with the sixth transmission member, and the sixth transmission member can drive the third transmission member to rotate in one direction.

[0019] Furthermore, a second one-way linkage member is fixedly provided at the output end of the central motor, the sixth transmission member is connected to the second one-way linkage member, and the central motor can drive the third transmission member to rotate through the second one-way linkage member.

[0020] The present invention also provides a torque detection method, comprising the following steps:

[0021] Obtain the bending moment of the supporting cantilever;

[0022] Obtaining the radial force of the second transmission member and the first transmission member in cooperation with each other, and the radial force of the fifth transmission member and the fourth transmission member in cooperation with each other, based on the bending moment of the support cantilever, the angle between the support cantilever and the line connecting the first transmission member and the second transmission member, and the distance between the center of the second transmission member and the other fixed end of the support cantilever;

[0023] deriving the circumferential force of the first transmission member and the circumferential force of the fourth transmission member based on the radial force of the first transmission member and the pressure angle of the first transmission member, and the radial force of the fourth transmission member and the pressure angle of the fourth transmission member, respectively, wherein the circumferential forces of the first transmission member and the first transmission member at the transmission position are equal, and the circumferential forces of the fourth transmission member and the fifth transmission member at the transmission position are equal;

[0024] The bending moment of the central shaft is obtained according to the radial force, circumferential force and radius of the first transmission member and the radial force, circumferential force and radius of the fourth transmission member.

[0025] Furthermore, the step of obtaining the bending moment of the supporting cantilever specifically includes:

[0026] The strain force of the supporting cantilever is obtained, and the bending moment of the supporting cantilever is obtained according to the strain force.

[0027] The beneficial effects achieved by the present invention are as follows: a first transmission member and a fourth transmission member are arranged on the central axis, a supporting cantilever is arranged on the vehicle body, and a second transmission member is rotatably arranged on the supporting cantilever to engage with the first transmission member and a fifth transmission member is engaged with the fourth transmission member to form a transmission. Since one end of the supporting cantilever is in a fixed posture, the resultant force of the radial force component of the second transmission member and the radial force component of the fifth transmission member can produce a certain bending phenomenon on the supporting cantilever. Further, by arranging a strain gauge on the supporting cantilever to detect the resistance change value of the supporting cantilever, the input bending moment of the central axis, that is, the force required for the central axis to drive the load, can be obtained. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 is a perspective view of the power assist device provided by the present invention;

[0029] Figure 2 yes Figure 1 Cross-section at AA;

[0030] Figure 3 It is a side view of the power assist device provided by the present invention. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0032] The present invention arranges a first transmission member on the central axis, arranges a supporting cantilever on the vehicle body, and rotatably arranges a second transmission member on the supporting cantilever to engage with the first transmission member and a fifth transmission member to engage with the fourth transmission member to form a transmission. The resultant force of the radial force component of the second transmission member and the radial force component of the fifth transmission member can produce a certain bending phenomenon on the supporting cantilever. Further, by arranging a strain gauge on the supporting cantilever to detect the resistance change value of the supporting cantilever, the input bending moment of the central axis, that is, the force required for the central axis to drive the load, can be obtained.

[0033] Example 1

[0034] See also Figure 1-3 The present invention provides a torque sensor for a mid-mounted motor of a power-assisted bicycle, characterized in that it includes a central axis 1, a first transmission member 2, a second transmission member 4, a third transmission member 61, a fourth transmission member 62, a fifth transmission member 63, a support cantilever 3, and a strain gauge 5. The central axis 1 is used to connect the pedals; the first transmission member 2 is fixed to the central axis 1 so as to be able to rotate with the central axis 1, the fourth transmission member 62 is rotatably mounted on the central axis 1, and the first transmission member 2 and the fourth transmission member 62 are arranged at intervals along the axial direction of the central axis to avoid mutual interference between the first transmission member 2 and the fourth transmission member during rotation; one end of the support cantilever 3 is fixed to the vehicle body, and the other end is rotatably provided with the second transmission member 4 and the fifth transmission member 63, the second transmission member 4 and the fifth transmission member 63 are coaxial and integrally arranged, and the second transmission member 4 and the first transmission member 4 are arranged in a coaxial and integral manner. 2 is engaged so that the rotation of the first transmission member 2 can drive the second transmission member 4 to rotate. The fifth transmission member 63 integrally provided with the second transmission member 4 is engaged with the fourth transmission member 62 to drive the fourth transmission member 62 to rotate. The fourth transmission member 62 and the fifth transmission member 63 are integrally provided to ensure that the radial forces exerted on the first transmission member 2 and the fourth transmission member 62 by the fourth transmission member 62 are uniformly transmitted to the support cantilever 3. The strain gauge 5 is provided on the support cantilever 3 to obtain the voltage change value generated by the strain gauge 5 when the support cantilever 3 transmits power between the first transmission member 2 and the second transmission member 4.

[0035] By arranging a first transmission member 2 and a fourth transmission member 62 on the central shaft 1, arranging a support cantilever 3 on the vehicle body, and rotatably arranging a second transmission member 4 and a fifth transmission member 63 on the support cantilever 3, the second transmission member 4 forms a transmission with the first transmission member 2, the fifth transmission member 63 forms a transmission with the fourth transmission member 62, and the fourth transmission member then drives the third transmission member to rotate in one direction, thereby forming a complete torque transmission. When the central shaft drives the first transmission member 2 to rotate to transmit force to the second transmission member 4, one end of the support cantilever is in a fixed posture, and the radial force component of the second transmission member 4 and the fifth transmission member 63 can cause a certain bending phenomenon to the support cantilever 3. Further, by arranging a strain gauge 5 on the support cantilever 3 to obtain the resistance change value generated by the strain gauge 5 when the support cantilever 3 is subjected to the combined force of the radial components of the second transmission member and the first transmission member, the input bending moment of the central shaft 1, that is, the force required for the central shaft 1 to drive the load, can be obtained.

[0036] The torque sensor provided by the present invention converts the dynamic torque on the central axis 1 in the existing structure into a stable bending moment for measurement through the transmission structure design of the bending moment. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

[0037] Specifically, the first transmission member 2 and the second transmission member 4 are both gears, and the first transmission member 2 and the second transmission member 4 are meshed for transmission, so that the transmission accuracy is high and the compactness of the structure and the stability of the bending moment transmission can be improved.

[0038] Specifically, one end of the support cantilever is provided with a square hole 35 for fixing to the vehicle body, that is, the square hole 35 can penetrate the first fixing plate 31, the fixing member 34 and the second fixing plate 32 described below in sequence, and a square member (not shown in the figure) can be used to cooperate with the square hole 35 to fix the support cantilever 3 on the vehicle body. In this way, the support cantilever 3 can be prevented from rotating around the square member during the operation of the first transmission member 2 and the second transmission member 4, thereby improving the accuracy of the strain gauge measurement data.

[0039] Specifically, the first transmission member 2 can be fixed on the central shaft 1 by means of a spline, a flat key or other fixing methods.

[0040] In this embodiment, the first transmission member 2 , the second transmission member 4 , the fourth transmission member 62 and the fifth transmission member 63 may all be gears.

[0041] Example 2

[0042] See also Figure 1Based on the first embodiment, the support arm 3 further includes a first fixing plate 31 and a second fixing plate 32 spaced apart from each other, and a connecting shaft 33 connecting the first fixing plate 31 and the second fixing plate 32. The second transmission member 4 and the fifth transmission member 63 are rotatably fixed to the connecting shaft 33. Thus, the first fixing plate 31 and the second fixing plate 32 can improve the force stability of the second transmission member 4 and the fifth transmission member 63, while also increasing the strength of the support arm 3, thereby extending its service life.

[0043] Furthermore, the support arm 3 includes a fixing member 34 that connects the first fixing plate 31 and the second fixing plate 32. The first fixing plate 31, the fixing member 34, and the second fixing plate 32 are used to secure the first fixing plate 31, the fixing member 34, and the second fixing plate 32 to the vehicle body. Thus, the fixing plates and the connecting shaft 33 work together to form the first fixing plate 31 and the second fixing plate 32 into a structurally reliable and stable whole, thereby improving the overall strength of the support arm 3 and facilitating its securement to the vehicle body.

[0044] Furthermore, the strain gauge 5 is arranged on opposite sides of the first fixed plate 31 and / or the second fixed plate 32 perpendicular to the axial direction of the connecting shaft 33. When the strain gauge 5 is arranged on the first fixed plate 31 and the second fixed plate 32, the accuracy of the numerical measurement of the strain gauge 5 can be enhanced, thereby improving the reliability of the product.

[0045] Example 3

[0046] See also Figure 1 The present invention also provides a power assist device, including a third transmission member 61 and the above-mentioned power assist sensor. The third transmission member 61 is rotatably arranged on the central axis 1 relative to the central axis 1 and is located on the side of the fourth transmission member 62 away from the first transmission member 2. The fourth transmission member 62 can drive the third transmission member 61 to rotate in one direction. The third transmission member 61 is used to connect the load, and the load is the wheel.

[0047] In this way, the fourth transmission member 62 unidirectionally drives the third transmission member 61 to rotate. When the user pedals, the torque applied to the center axle 1 is transmitted from the fourth transmission member 62 to the third transmission member 61, thereby driving the load, i.e., the wheel, to rotate. However, when the wheel is assisted, the third transmission member 61 does not drive the fourth transmission member 62 to rotate, thereby preventing the load from being transferred to the center axle 1.

[0048] Specifically, the third transmission member 61 is connected to the central axis 1 through the second bearing 30 and the third bearing 40, wherein the second bearing 30 and the third bearing 40 are located at both ends of the third transmission member 61, that is, the second bearing 30 or the third bearing 40 is arranged on the connecting part to facilitate the installation of the third transmission member 61 on the central axis 1.

[0049] Furthermore, the third transmission member 61 is provided with a load connecting member 7 for connecting a load.

[0050] In this embodiment, the load connection member 7 may be a chainring.

[0051] Specifically, the third transmission member 61 is provided with a connecting portion, on which the first one-way linkage member 8 is provided. The fourth transmission member 62 is fixedly mounted on the first one-way linkage member 8. The fourth transmission member 62 can drive the third transmission member 61 in a coordinated manner via the first one-way linkage member 8. In this way, the rotation of the central shaft drives the fourth transmission member 62 to rotate, and the fourth transmission member 62 can drive the third transmission member 61 to rotate via the first one-way linkage member 8. When the central motor inputs power to the central shaft, the third transmission member 61 cannot drive the fourth transmission member 62 to rotate, thereby preventing the transfer of load to the central shaft 1.

[0052] The power assist device provided by the present invention converts the dynamic torque on the central axis 1 into a stable bending moment for measurement through the transmission structure design of the bending moment. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

[0053] In this embodiment, the first one-way linkage member 8 can be a one-way bearing.

[0054] Example 4

[0055] See also Figure 1 The present invention also provides a power-assisted bicycle comprising a bicycle body, a mid-mounted motor (not shown), and the aforementioned power-assisting device. The mid-mounted motor is mounted on the bicycle body, and a sixth transmission member 9 is provided at the output end of the mid-mounted motor. A third transmission member 61 engages with the sixth transmission member 9, and the sixth transmission member 9 can unidirectionally drive the third transmission member 61 for rotation.

[0056] Thus, when a bending moment is input to the center shaft 1, the third transmission member 61 does not drive the sixth transmission member 9 to rotate, nor does it drive the output end of the center motor to rotate, thereby avoiding increasing the load on the human end by dragging the motor. When the center motor rotates, it can drive the sixth transmission member 9, which in turn drives the third transmission member 61, thereby driving the load connector 7, thereby reducing the load on the input end of the center shaft 1 and producing a power-assisting effect.

[0057] The power-assisted bicycle provided by the present invention converts the dynamic torque on the central axis 1 into a stable bending moment for measurement through the transmission structure design of the bending moment. Compared with the existing technology, there is no need to use wireless torque transmission, and there is no risk of wireless power supply and wireless communication. The torque acquisition is highly reliable and the cost is low.

[0058] See also Figure 2Specifically, a second one-way linkage 10 is fixedly provided at the output end of the central motor, and the sixth transmission member 9 is connected to the second one-way linkage 10. The central motor can drive the third transmission member 61 to rotate via the second one-way linkage 10. Thus, the sixth transmission member 9 is connected to the central motor via the second one-way linkage 10. When the third transmission member 61 rotates, the sixth transmission member 9 is driven by the third transmission member 61 into an idling state. That is, the sixth transmission member 9 does not drive the output end of the central motor to rotate. Instead, the driving force output by the output end of the central motor can drive the sixth transmission member 9 to rotate via the second one-way linkage 10, thereby driving the third transmission member 61 to rotate, thereby driving the load end to rotate, thereby providing assistance to the central shaft 1.

[0059] In this embodiment, the second one-way linkage 10 can be a one-way bearing.

[0060] Example 5

[0061] See also Figure 3 The present invention also provides a torque detection method, comprising the following steps:

[0062] S1: Obtain the bending moment Mr of the supporting cantilever 3. Specifically, obtain the strain force of the supporting cantilever 3, and obtain the bending moment Mr of the supporting cantilever 3 according to the strain force.

[0063] According to the general measurement method of the strain gauge 5 , the bending moment Mr received by the supporting cantilever 3 can be measured and calibrated by the strain gauge 5 on the supporting cantilever 3 .

[0064] S2: Based on the bending moment Mr of the support cantilever 3, the angle β between the support cantilever 3 and the line connecting the first transmission member 2 and the second transmission member 4, and the distance L from the center of the second transmission member 4 to the fixed end of the support cantilever 3, the radial force of the coordinated transmission between the second transmission member 4 and the first transmission member 2, and the radial force of the coordinated transmission between the fifth transmission member 63 and the fourth transmission member 62 are obtained;

[0065] The bending moment Mr on the supporting cantilever 3 is generated by the radial force of the second transmission member 4 and the fifth transmission member 63. That is, if the radial force of the first transmission member 2 on the second transmission member 4 is Fr1, then the radial force of the second transmission member 4 on the first transmission member 2 is the reverse force, set as Fr1". If the radial force of the fourth transmission member 62 on the fifth transmission member 63 is Fr2, then the radial force of the fifth transmission member 63 on the fourth transmission member is the reverse force, set as Fr1". Then the resultant force of the component force of the radial force Fr1 (Fr12)) and the component force of the radial force Fr2 (not shown in the figure) on the supporting cantilever 3 generates a bending moment Mr. Since the first transmission member and the fourth transmission member are coaxial and the second transmission member and the fifth transmission member are coaxial, the angle between the supporting cantilever and the line connecting the fourth transmission member and the fifth transmission member is also β, where β is the acute angle between the supporting cantilever 3 and the center line of the meshing of the transmission member.

[0066] According to the calculation formula: Mr = (Fr1 + Fr2) * sinβ * L, the value of Fr2 can be calculated.

[0067] S3: Obtaining the circumferential force Ft1 of the first transmission member 2 according to the radial force Fr1 of the first transmission member 2 and the pressure angle α of the first transmission member 2, wherein the circumferential forces of the first transmission member 2 and the second transmission member 4 at the transmission positions are equal;

[0068] According to the radial force Fr2 of the fourth transmission member 62 and the pressure angle α of the fourth transmission member 62, the circumferential force Ft2 of the fourth transmission member 62 is obtained, wherein the circumferential forces of the fourth transmission member 62 and the fifth transmission member 63 at the transmission position are equal;

[0069] According to the calculation formula:

[0070] Fr=Fr1+Fr2;

[0071] Ft1=Fr1 / tanα;

[0072] Ft2=Fr2 / tanα;

[0073] We can get: Ft1+Ft2=Fr / tanα

[0074] The pressure angle α is a fixed value of the mechanical parameter of the transmission member, and the pressure angles of the first transmission member 2, the second transmission member 4, the fourth transmission member 62, and the fifth transmission member 63 that cooperate with each other are the same, which is α.

[0075] S4: Obtain the bending moment of the central shaft 1 according to the radial force Fr1, the circumferential force Ft1 and the radius R1 of the first transmission member 2, and the radial force Fr2, the circumferential force Ft2 and the radius R2 of the fourth transmission member 62.

[0076] According to the force analysis of the central shaft 1, the bending moments of the first transmission member 2 and the fourth transmission member 62 fixed on the central shaft 1 are both the bending moments of the central shaft 1.

[0077] According to the calculation formula:

[0078] M=Ft1*R1

[0079] M=Ft2*R2

[0080] We can get: M / R1+M / R2=Fr / tanα

[0081] Thus we get: M = Fr*R1*R2 / [(R1+R2)*tanα] = Mr*R1*R2 / [(R1+R2)*tanα*sinβ*L]

[0082] Example 8

[0083] On the basis of the seventh embodiment, further, the step of obtaining the bending moment of the supporting cantilever 3 specifically includes:

[0084] S11: Obtain the strain force of the supporting cantilever 3, and obtain the bending moment Mr of the supporting cantilever 3 based on the strain force. The resistance change generated by the strain gauge 5 when the supporting cantilever 3 is subjected to force is obtained by setting the strain gauge 5 on the supporting cantilever 3, thereby obtaining the generated bending moment Mr.

[0085] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A torque sensor for a mid-mounted motor of a power-assisted bicycle, characterized in that: include: The middle bracket is used to connect the pedals; a first transmission member and a fourth transmission member, wherein the first transmission member is fixed to the central shaft, the fourth transmission member is rotatably sleeved on the central shaft, and the first transmission member and the fourth transmission member are arranged in an axial direction of the central shaft at intervals; A support cantilever, one end of which is fixed to the vehicle body, and the other end of which is rotatably provided with a second transmission member and a fifth transmission member, the second transmission member and the fifth transmission member being coaxial and integrally arranged, the second transmission member being engaged with the first transmission member, and the fifth transmission member being engaged with the fourth transmission member; a strain gauge, provided on the supporting cantilever, for obtaining a voltage change value generated by the strain gauge when the supporting cantilever is driven by the first transmission member and the second transmission member; The supporting cantilever includes a first fixing plate and a second fixing plate that are spaced apart, and a connecting shaft connecting the first fixing plate and the second fixing plate. The second transmission member and the fifth transmission member are rotatably fixed on the connecting shaft.

2. The torque sensor according to claim 1, wherein: The supporting cantilever further includes a fixing member, which connects the first fixing plate and the second fixing plate and is used for fixing to the vehicle body.

3. The torque sensor according to claim 1, wherein: The strain gauges are arranged on two opposite sides of the first fixing plate and / or the second fixing plate that are perpendicular to the axis direction of the connecting shaft.

4. A power assist device, characterized in that: It includes a third transmission member and a torque sensor as described in any one of claims 1 to 3, wherein the third transmission member can be rotatably arranged on the central axis relative to the central axis and is located on the side of the fourth transmission member away from the first transmission member, the fourth transmission member can drive the third transmission member to rotate in one direction, and the third transmission member is used to connect the load.

5. The power assist device according to claim 4, characterized in that: The third transmission member is provided with a connecting portion, the connecting portion is provided with a first one-way linkage member, the fourth transmission member is fixed to the first one-way linkage member, and the fourth transmission member can drive the third transmission member to link with the first one-way linkage member.

6. A power-assisted bicycle, characterized in that: include: body; a central motor, disposed on the vehicle body, wherein an output end of the central motor is provided with a sixth transmission member; as well as According to the power assist device as described in claim 4 or 5, the third transmission member is engaged with the sixth transmission member, and the sixth transmission member can drive the third transmission member to rotate in one direction.

7. The power-assisted bicycle according to claim 6, wherein: The output end of the central motor is fixedly provided with a second one-way linkage member, the sixth transmission member is connected to the second one-way linkage member, and the central motor can drive the third transmission member to rotate through the second one-way linkage member.

8. A torque detection method, used for the torque sensor according to any one of claims 1 to 3, characterized in that: The following steps are involved: Obtain the bending moment of the supporting cantilever; Obtaining the radial force of the second transmission member and the first transmission member in cooperation with each other, and the radial force of the fifth transmission member and the fourth transmission member in cooperation with each other, based on the bending moment of the support cantilever, the angle between the support cantilever and the line connecting the first transmission member and the second transmission member, and the distance between the center of the second transmission member and the other fixed end of the support cantilever; deriving the circumferential force of the first transmission member and the circumferential force of the fourth transmission member based on the radial force of the first transmission member and the pressure angle of the first transmission member, and the radial force of the fourth transmission member and the pressure angle of the fourth transmission member, respectively, wherein the circumferential forces of the first transmission member and the first transmission member at the transmission position are equal, and the circumferential forces of the fourth transmission member and the fifth transmission member at the transmission position are equal; The bending moment of the central shaft is obtained according to the radial force, circumferential force and radius of the first transmission member and the radial force, circumferential force and radius of the fourth transmission member.

9. The torque detection method according to claim 8, wherein: The step of obtaining the bending moment of the supporting cantilever specifically includes: The strain force of the supporting cantilever is obtained, and the bending moment of the supporting cantilever is obtained according to the strain force.

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